This invention relates to an improved, fluid driven tool and more particularly to an air tool of the type having a rotary vane, air motor with an improved automatic fluid shut-off mechanism for controlling the flow of inlet fluid to the motor.
Rotary vane air motors are often incorporated in air tools such as nut runners, screwdrivers and the like. Typically such air tools incorporate a rotary vane air motor which operates in response to a manually operated pneumatic control valve. The air motor drives a central shaft which serves as the output shaft for the tool.
Heretofore various mechanisms had been proposed for controlling the speed of such tools by automatically shutting the rotary vane air motor off if the motor operates at an excessive speed. Mechanisms have also been proposed to control the torque output of such a motor and to provide other various control features in association with such a motor.
Nonetheless, there has remained a need for improved controls associated with such air tools. Among the controls desired is a mechanism which will automatically turn the tool off consistently when the torque output of the tool reaches a predetermined value. Additionally, it is desirable to provide a rotary shaft tool which will operate in reverse wihout torque control. Further, a feature desired for such tools is a mechanism for bypassing the torque control mechanism and to permit start up of the air tool without a complicated reset mechanism. In sum, an improved torque control mechanism is desired for incorporation in a rotary vane air motor tool of the type having a single output shaft mounted on bearings.